High accuracy molded navigation arrays, systems, and methods

ABSTRACT

Systems, methods, and devices are described for high accuracy molded navigation arrays. In example embodiments, a navigation array may be formed by molding, as a single component, an array having a plurality of marker regions that may include a reflective layer disposed thereon. In other embodiments, a navigation array may be formed by molding over a frame having a plurality of marker elements. In still other embodiments, a navigation array may be formed by molding over individual marker elements. In certain embodiments, a navigation array may be formed by molding a frame with a plurality of voids and subsequently molding marker elements into each void where the marker elements may include a reflective layer disposed thereon. In some embodiments, a navigation array may be formed by molding a plurality of marker elements on a frame and disposing a reflective layer on the marker elements.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Patent ApplicationNo. 63/124,687, filed Dec. 11, 2020, the disclosure of which isincorporated herein by reference in its entirety.

BACKGROUND

Many different surgical procedures utilize some form of surgicalnavigation or tracking to aid in positioning surgical instrumentsrelative to portions of patient anatomy during a procedure. Robotic orrobot-assisted surgical procedures are an important example of such asurgical procedure, as surgical navigation is crucial for correctlypositioning a robotically controlled or assisted surgical instrumentrelative to a patient. For example, in such a system, optical navigationor tracking systems may utilize stereoscopic sensors to detect infra-red(IR) light reflected or emitted from one or more optical markers affixedto surgical instruments and/or portions of a patient's anatomy. Anavigation array or tracker having a unique constellation or geometricarrangement of reflective elements may be coupled to a surgicalinstrument and, once detected by stereoscopic sensors, the relativearrangement of the elements in the sensors' field of view, incombination with the known geometric arrangement of the elements, mayallow the system to determine a three-dimensional position andorientation of the tracker and, as a result, the instrument or anatomyto which the tracker is coupled. For example, the array may be mounted(e.g., integrally or removably) on an instrument, and the instrument maybe received and/or controlled by a robot arm. Navigation systems mayidentify a position of the instrument.

Navigation arrays often comprise multi-component structures that includeat least a frame and reflective navigation markers adapted to be coupledthereto before use. In some cases, for example, a navigation array mayinclude posts or protrusions mounted on the frame, the posts configuredto be received within a recess formed in a reflective navigation marker,and the frame and marker components joined together. However, asaccuracy is a paramount consideration in surgical navigation, it can beappreciated that multi-component structures may be associated withcertain drawbacks. For example, poor dimensional tolerances of eitherthe frame, reflective navigation marker, or user error in assembly, caneach affect accuracy, and thus impact navigation performance of arobotic surgical system. Moreover, some navigation arrays experiencesignificant forces (e.g., such as vibration) during the surgicalprocedure, which may allow multi-component structures to becomerelatively loosened, which affects accuracy.

Accordingly, there is a need for improved systems, methods, and devicesfor creating high accuracy navigation arrays that may be utilized totrack (e.g., accurately) surgical instruments, patient anatomy, or othercomponents during a surgical procedure.

SUMMARY

Systems, methods, and devices are disclosed for a navigation array, suchas for use in a computer-assisted surgical system, the array comprisinga monolithic array body comprising a nonreflective frame region, and aplurality of spaced apart marker regions, wherein each of the markerregions has an associated reflective element configured to be detectedand tracked by an optical tracking sensor.

In yet another example, a computer assisted surgical system comprisesthe above-described navigation array, an optical tracking unitassociated with at least one optical tracking sensor, and a controlunit, wherein the control unit may be adapted to utilize a predeterminedfixed geometric relationship between the marker regions and detectedpositions of the marker regions to determine a three-dimensionalposition and orientation of the navigation array. The computer assistedsurgical system may further comprise a robot arm and a surgicalinstrument mounted to the robot arm. The navigation array may be adaptedto be mounted to the robot arm or the surgical instrument.

In yet another example, a method manufacturing a navigation arraycomprises injection molding, in a single operation, the monolithic arraybody. In yet another example, a method manufacturing a navigation arraycomprises over molding the monolithic array body over a navigationmarker sub-assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic of a robotic surgical system;

FIGS. 2A and 2B show a pair of surgical navigation array frames that maybe part of multi-component (e.g., non-monolithic) navigation array;

FIGS. 3A and 3B show a monolithic navigation array;

FIG. 4A shows another embodiment of a monolithic navigation array;

FIGS. 4B and 4C show sectional views of the monolithic navigation arrayof FIG. 4A after molding and after application of a reflective materialin select areas, respectively;

FIG. 5 shows a sectional view of a navigation marker region formed in amonolithic navigation array;

FIG. 6 shows another embodiment of a monolithic navigation array and adetail sectional view taken along a line F-F;

FIG. 7 shows another embodiment of a monolithic navigation array and adetail sectional view taken along a line F-F;

FIG. 8A shows another embodiment of a monolithic navigation array;

FIG. 8B shows a sectional view of a navigation marker region of thenavigation array of FIG. 8A along the line 8B-8B;

FIG. 9 shows another embodiment of a monolithic navigation array;

FIG. 10 shows another embodiment of a monolithic navigation array;

FIG. 11A shows another embodiment of a monolithic navigation array;

FIG. 11B shows an elevational view of the monolithic navigation array ofFIG. 11A;

FIG. 11C shows a plan view of the monolithic navigation array of FIG.11A;

FIG. 11D shows a sectional view of a navigation marker region of thenavigation array of FIG. 11B along the line 11D-11D;

FIG. 12 shows another embodiment of a monolithic navigation arrayhaving, inter alia, an over molded insert;

FIG. 13 shows a cut away view of another embodiment of an over moldedinsert;

FIG. 14 shows a cut away view of another embodiment of an over moldedinsert;

FIG. 15 shows a cut away view of another embodiment of an over moldedinsert;

FIG. 16A shows a cut away view of another embodiment of an over moldedinsert;

FIG. 16B shows a partial sectional view of the insert of FIG. 16A alongthe line 16B-16B;

FIG. 17 shows a navigation marker sub-assembly;

FIG. 18 shows a cut away view of another embodiment of a monolithicnavigation array molded over the navigation marker sub-assembly of FIG.17;

FIG. 19 shows a schematic of a method for molding a navigation arrayusing a navigation marker sub-assembly;

FIG. 20 shows another embodiment of a navigation marker sub-assembly;

FIG. 21 shows an elevational view of the navigation marker sub-assemblyof FIG. 20;

FIG. 22 shows a cut away view of another embodiment of a monolithicnavigation array molded over the navigation marker sub-assembly of FIG.20;

FIG. 23 shows another embodiment of a navigation marker sub-assembly;

FIG. 24 shows navigation markers disposed in the navigation markersub-assembly of FIG. 23; and

FIG. 25 shows a schematic of a method for molding a navigation arrayusing individual navigation markers.

DETAILED DESCRIPTION

Devices, systems, and methods for high accuracy navigation arrays aredisclosed herein. In some embodiments, high accuracy navigation arraysare created by molding the array as a monolithic unit that includes aplurality of navigation marker regions spaced apart in a desiredgeometric relationship. “Monolithic,” as used herein, refers to cast ormolded as a single piece (e.g., a single part), preferably,injection-molded. As will be described, the monolithic navigation arraysof the present disclosure may be molded from a single material or may beof multiple materials molded together.

Molding a navigation array may provide advantages because the singlepart's dimensions may be tightly controlled with regard to tolerancesand the molding process may be highly repeatable. In addition, there isgreater flexibility to manufacture navigation arrays of various sizesaccording to need (e.g., for affixing to different size instrumentation,anatomy, or other components). The devices, systems, and methodsdisclosed herein provide a variety of different molded high accuracynavigation arrays, including arrays molded using a single material,arrays molded with multiple materials for different regions, arraysmolded over other parts, such as an assembly of pre-existing navigationmarkers, various array tips or other inserts, etc., and arrays moldedover a plurality of individual or separate components, such as an arraymolded over a plurality of pre-existing navigation markers that are notcoupled to one another in an assembly.

Example embodiments of the present disclosure provide methods ofmanufacturing navigation arrays with a consistently low tolerances bymanufacturing the array and the navigation markers into one single partusing an injection molding process, where the tolerance of the moldingoperation is primary responsible for the resultant tolerance in theposition between the navigation markers. The molded array may havemultiple portions, or navigation marker regions, that are designed to beclear (e.g., formed from polycarbonate) and subsequently receive areflective treatment in order to form a navigation marker in the clearregion of the array. For example, in molding a navigation array,multiple regions may be formed as full or half sphere lenses, withexteriors of those regions receiving a reflective material coating in asubsequent step to form a navigation marker (e.g., a lens and areflective surface behind the lens). The use of a single moldingoperation to define the relative locations of the navigation markers mayenable the accuracy between the reflective portions to achieve desiredtolerances, e.g., +/−0.05 mm in some embodiments. Moreover, becauseinjection molding processes are repeatable using the same mold, theconsistency of the tolerances across multiple arrays formed by thisprocess may be extremely high.

Each of these arrays may be a monolithic component that lacks amechanical interface capable of easy disassembly or re-assembly. Asnoted above, molding the navigation arrays disclosed herein as a singlepiece may provide distinct advantages in eliminating drawbacks ofconventionally-assembled arrays with regard to positional tolerancing,etc. This may be important for optimal navigation tracking performance,as surgical navigation systems may require tolerances below about 0.1 mmfor placement of reflective elements in some embodiments, and belowabout 0.05 mm for placement of reflective elements in certainembodiments. Conventional approaches, e.g., multi-component navigationarrays, may often fail to achieve better than about 0.15 mm tolerance inpositioning reflective elements, and in some embodiments may be producepositioning tolerance of about 0.2 mm or greater in positioningreflective elements. This may introduce errors and inaccuracies intracking instruments, anatomy, or other components coupled to suchnavigation arrays.

The presently disclosed navigation arrays may be employed withcomputer-assisted surgical (CAS) systems, for example, robotic surgicalsystems. Such systems may utilize any of surgical navigation/trackingand robot control or assistance to monitor or control movement of one ormore surgical instruments during a procedure. While the illustratedembodiments and accompanying description do not make particularreference to a specific surgery, the systems and methods describedherein may be utilized in various applications involving robotic,robot-assisted, and non-robotic operations where computer-assisted toollocation are required and precise adjustment of tool position may beappropriate. Example applications include knee surgery, e.g., total kneearthroplasty (TKA) or unicompartmental knee arthroplasty (UKA), hipsurgery, e.g., hip arthroplasty, shoulder surgery, spine surgery, etc.The teachings of the present disclosure may be applied to suchprocedures; however, the systems and methods described herein are notlimited to these applications.

FIG. 1 shows a schematic of a robotic surgical system, comprising arobotic device 100, including a surgical robot arm 1001, that includesan attached tool end effector 110 and a plurality of arm segments 101connected by rotatable or otherwise articulating joints 109. Adistal-most segment of the robot arm may include a navigation array 200mounted thereto adjacent to the tool end effector 110. As can beappreciated, positions of the end effector can be determined withrespect to the patient or to the robotic device.

A global coordinate system 11 of the robotic device 100 may be defined,as well as an end effector coordinate system 12. The global coordinatesystem 11 may be defined in different ways and, in some embodiments, mayuse the location of a base 10 of the robotic device 110, which may ormay not itself be stationary, as an origin. The location of thedistal-most arm segment of the robotic device may be calculated byreceiving a position signal from an encoder in each joint 109 and/or bymeasuring a position of the navigation array 200 to directly detect theposition of the arm segment and determine the position of the distal endthereof in the global coordinate system. In some instances, a measuredcoordinate system of the navigation array 200 may be different from theglobal coordinate system 11 and calculations may be utilized toharmonize the two coordinate systems. In some embodiments, the measuredcoordinate system may be used as the global coordinate system 11.

The end effector coordinate system 12 may be defined in different waysbut may refer to the position and orientation of the tool end effector110 with respect to the operation of the tool end effector (e.g., if thetool end effector includes a cutting bit, the cutting direction may bealong an “up” or “down” axis that might be defined by, e.g., alongitudinal axis of the tool). The tool end effector 110 held by therobotic device 100 may be constrained to move about the distal end ofthe distal-most arm segment such that the summation of the positions ofjoints 109 may define the location of the end effector coordinate system12 in the global coordinate system 11 with respect to a control systemof the joints 109 to control movement of the tool end effector 110.

Accordingly, the robotic device 100 may be connected to a control unit300 that controls, inter alia, the actuation of each joint 109 in orderto position the tool end effector 110. The control unit 300 typicallycomprises power supply, AC/DC converters, motion controllers, and othercomponents to power the motors of the actuation units in each joint 109,as well as fuses, real-time control system interface circuits, and othercomponents typically included in surgical robotic devices. Further, thepresent disclosure is also contemplated to include use of suchinstruments by surgical robots, by users with some degree of roboticassistance, and without involvement of surgical robots or roboticassistance (e.g., where solely surgical navigation/tracking isutilized).

Further, in some embodiments additional and/or alternative navigationarrays may be employed in addition to, or in place of, the navigationarray 200 shown attached to a distal-most arm segment 101 of the robotarm 1001. For example, in some embodiments a navigation array 202 may becoupled to another component of the robotic device, such as a base ofthe robot arm 1001 in embodiments where the robot is mobile. Stillfurther, a navigation array 204 may be coupled to the tool end effectoritself. In embodiments where a single tool is provided, the array 204may be coupled directly thereto.

A tracking unit 50 is provided, such that the relative pose orthree-dimensional position and orientation of the navigation arrays 200,202, and/or 204 (or other arrays) may be tracked in real time and sharedto the control unit 300 and any additional planning or control system.In some instances, coordinate systems may be attached to the roboticdevice 100 via the navigation array 200, the end effector 110 via thearray 204, and an anatomical structure (not shown). The tracking unit 50may measure the relative motions between any and all coordinate systemsin real time. Real time may, in some embodiments, mean high frequenciesgreater than twenty Hertz, in some embodiments in the range of onehundred to five hundred Hertz, with low latency, in some embodimentsless than five milliseconds. For example, the navigation arrays mayinclude, for example, optical trackers comprising reflective or activemarkers detected by a sensor 51 in view of the surgical field. Thetracking unit 50 may include a passive optical tracker consisting of,for example, a constellation of reflective tracking elements having afixed geometric relationship that may be coupled to a portion of patientanatomy, a surgical instrument, or other component to be tracked. Thetracking unit 50 may include a stereoscopic sensor having two or morephysically separated detectors 51 that may be used to detect lightreflected off each of the tracking elements (e.g., reflected infra-red(IR) light in some embodiments). The sensor 51, in some embodiments inconjunction with other information processing components such as thecontrol unit 300, may utilize the known fixed geometric relationshipbetween the tracking elements and the detected positions of the trackingelements to determine a precise three-dimensional position andorientation of the navigation array(s), and therefore, of the entitycoupled to the array.

In some embodiments, in place of, or in addition to, the above-describedreflective optical tracking, optical tracking may be employed usingactive light emitters, such as light emitting diodes (LEDs). In otherembodiments, electromagnetic trackers may be employed, while in stillother embodiments any of inertial sensors using gyroscopic measurements,ultrasonic sensors, radio-frequency identification (RFID) sensors, orother known sensors may be employed.

FIGS. 2A and 2B show a pair of surgical navigation array frames 200 (athree-marker frame) and 210 (a two-marker frame) that may be part ofmulti-component (e.g., non-monolithic) navigation arrays. Such arrayshave posts 201 to receive markers, such as the above-described opticaltrackers (not depicted). For example, in many instances navigationarrays make use of commercially available optical reflective elements,such as the NDI Radix™ Lens, which have a body with a hemisphericalpolycarbonate lens opposite a larger hemispherical element with areflective surface that is visible through the hemispherical lens.Corresponding recesses of the optical trackers receive the posts 201 andthe two components may be joined using adhesives, ultrasonic welding,mechanical fastening (e.g., threads), etc. However, it may be difficultto position optical markers relative to the navigation array frames in amanner that achieves tolerances needed for optimal surgical navigationtracking performance. For example, in some cases a recess formed in anoptical marker may be larger than the post 201. As a result, the opticalmarker (e.g., reflective navigation marker) may move about the postduring assembly and end up in a position sufficiently far from itsdesired position. Further, tolerances for each component may stack oradd together to produce a more significant variation in positioning. Ascan be appreciated, in an array that requires a post to attach to themarker (see FIGS. 2A and 2B) typically results in one-sided navigationmarkers, so that separate “left” and “right” navigation arrays arenecessary to point the marker toward an expected camera location.

FIGS. 3A and 3B illustrate an embodiment of a monolithic navigationarray 302 according to the present disclosure that may exhibit highaccuracy and address the drawbacks noted above. The illustratedembodiment is a single molded component that includes a frame 304 and aplurality of marker regions 306 located a distance apart from eachother. The array 302 may have any of a variety of shapes and sizes. Asillustrated, the frame 304 has a generally triangular shape, casting thethree marker regions 306 in a unique constellation of predetermineddimensions. Fewer or additional marker regions may be included and theshape of the frame 304 may be adjusted accordingly to accommodate themarker regions 306 and position them in a unique constellation ofpredetermined dimensions. Each marker region 306 may include a partialsphere that may have a hemispherical shape.

The array 302 may be molded in a single operation, e.g., by injectionmolding using any of a variety of suitable polymers, such as Polysulfone(PSU), Polyether Ether Ketone (PEEK), etc. to make a plastic. Further,the marker regions 306 may be provided with a reflective material (e.g.,coating) after molding to afford optical reflective navigation markers,such that a tracking unit (such as the tracking unit 50 of FIG. 1) maydetect them. The remainder of the frame 304 of the array 302 may have amatte finish that is not detectable. A neck 308 of the array 302terminates in a distal end 310. The end 310 may be configured to couplewith, e.g., a surgical instrument to be tracked or navigated.Alternatively, the end 310 may be pointer tip or other tip that may beused to register anatomy or other components in the surgical field withthe navigation system.

FIG. 4A is an illustration of another embodiment of a monolithicnavigation array 430 that includes a frame 431 and a plurality of markerregions 432 located a distance apart from each other. A navigationmarker lens 439 is disposed in each of the marker regions 432. The frame431, marker regions 432, and navigation marker lens 439 may be moldedfrom a single material in a single molding operation to control theposition of each navigation marker lens 439 with respect to each otherto the lowest tolerance possible (e.g., the tolerance of the moldingmachine and/or molding operation).

FIG. 4B shows a cross-section of the array 430 with the distance betweeneach navigation marker lens 439 indicated as L1. The tolerance of thisdistance L1, and therefore the overall accuracy of the navigation array,is limited only by the molding operation and the material properties ofthe material used to mold the array 430. As such, the array 430 is ahighly accurate array.

At FIG. 4C, a rear side of each navigation marker lens 439 may be coatedwith a reflective material 441 in order to form an optical marker 440from the combined arrangement of the navigation marker lens 439 andreflective material 441. FIG. 4C shows a distance between eachnavigation marker 440 indicated as L1. The tolerance of this distanceL1′, and therefore the overall accuracy of the navigation array, may bethe same as the tolerance of L1, as controlled by the single moldingoperation. The material used to mold the navigation array 430 may betranslucent or transparent to one or more wavelengths of light in orderfor light rays (e.g., those emitted by a light source of a trackingsystem and/or subsequently observed by a sensor of the tracking system)to pass through the navigation marker lens 439 and reflect off thereflective material 441. In other embodiments, the material used to moldthe navigation array 430 may be opaque and a reflective material may beapplied to one or both sides of the navigation marker 440 to enable anavigation system tracking unit to detect the marker.

FIG. 5 illustrates a sectional view of a navigation marker region 502formed in a monolithic (e.g., molded) navigation array 504 (e.g., suchas described herein). In this embodiment, the navigation marker region502 and a surrounding frame 506 are formed from a same material, e.g., asingle piece, single material, array 504. A variety of navigation markershapes may be employed, including the illustrated dual hemisphericalsurfaces that include an upper hemispherical surface 508 of a firstdiameter and a lower hemispherical surface 510 of a second diameter. Insome embodiments, the lower hemispherical surface 510 may includevarious features formed thereon, such as a roughened surface thatinteracts with light differently from a smooth surface, etc. One or moreof the upper hemispherical surface 508 and the lower hemisphericalsurface 510 may include a reflective material disposed thereon to aid atracking unit in detecting the navigation marker.

The high accuracy navigation arrays disclosed herein may utilize any ofa variety of navigation marker shapes and sizes. For example, upper andlower hemispherical surfaces may be of equal diameters or nonequaldiameters. Although the above-described embodiments are spherical, insome embodiments, the presently described monolithic navigation arraysmay utilize non-spherical navigation markers or a combination ofspherical and non-spherical navigation markers.

FIG. 6 shows a monolithic navigation array 600 having a plurality ofnon-spherical navigation markers 602. As can be seen in the detailsectional view taken along a line F-F, the navigation marker 602 hasunequal diameters between its upper and lower sections.

FIG. 7 shows a monolithic navigation array 700 having a plurality ofnon-spherical navigation markers 702 and a plurality of sphericalnavigation markers 704. As can be seen in the detail sectional viewtaken along a line F-F, the navigation marker 702 has unequal diametersbetween its upper and lower sections. In some embodiments, differentshapes and/or sizes of navigation markers may be utilized to aid asurgical navigation system in more quickly recognizing anddistinguishing between different arrays in its field of view.

In some embodiments, high accuracy navigation arrays may be molded frommultiple materials into a single, monolithic navigation array whereindifferent regions are formed from different materials.

FIGS. 8A and 8B show another embodiment of a monolithic navigation array800. The array 800 is molded using two different materials, e.g., amatte-finish opaque material for the frame 802 and a transparentmaterial for each of the navigation markers 804. An example method forproducing the navigation array 800 may include a two-part moldingoperation that includes, for example, first molding the frame 802 usinga plastic injection process and a matte opaque plastic, such asPolyether Ether Ketone (PEEK), Polysulfone (PSU), etc. Once the firstmaterial has sufficiently cooled following injection molding, thenavigation markers 804 may be molded using a different transparentmaterial, such as polycarbonate. In some embodiments, it may bedesirable that the molding temperature of the material used to form theframe 802 is higher than the molding temperature of the material used toform the navigation markers 804, such that the second injection moldingprocess does not melt the initially molded frame. Further, the shapeutilized for the second molding operation may an undercut or otherspecial shape to allow space for the material. In another embodiment, anacrylic material, such as Polymethyl Methacrylate (PMMA) orN,N-methylene-bis-acrylamide (MBA), may be utilized to perform overmolding using a same material. In such an embodiment, for example,spherical navigation marker shapes may be in a core closure to havehermeticity, and chemical links may be formed with melting flows duringthe second injection.

FIG. 8B, in particular, illustrates a detail sectional view showing thedifferent materials utilized in forming the navigation marker 804 andthe navigation array frame 802. This embodiment also illustrates anavigation marker lens design unequal diameters between its upper andlower sections. At least one of these sections may be coated with areflective material to enable a tracking unit to detect the navigationmarker.

The molding processes disclosed herein may allow the formation of highaccuracy navigation arrays at any desired size because both the frameand navigation markers are molded together. These may include arraysthat utilize larger and smaller navigation makers than are commerciallyavailable to users.

FIGS. 9 and 10 illustrate an example of a larger and smaller array,respectively. The navigation array 900 in FIG. 9 may have a frame 902that spans 300 mm or more in overall length and may include navigationmarkers 904 that are about 13 mm in diameter, for example. In contrast,the navigation array 1000 in FIG. 10 may have a frame 1002 that spansbetween about 20 and about 30 mm in overall length and may includenavigation markers 1004 that are about 5 mm in diameter, for example. Ofcourse, any of a variety of sizes are possible, including, for example,arrays between about 50 mm and about 500 mm in overall length. As notedabove, such arrays may include different numbers of navigation markers(of the same or different shapes) arranged in different geometricconfigurations. The ability to create custom and varying sizes ofnavigation arrays that include appropriately scaled navigation markersizes may be helpful in tracking different types of instruments,portions of patient anatomy, or other components in a surgical field.For example, attaching a relatively large navigation array to arelatively smaller, more delicate surgical instrument may make operationof the instrument unwieldy for a user. In some instances, use of smallernavigation markers may introduce difficulties for the tracking unit todetect the markers and monitor the navigation array, but in many casessuch issues may be resolved by repositioning the tracking unit to becloser to the arrays in use.

Another feature of the molded high accuracy navigation arrays disclosedherein is that they may be formed with navigation markers that may bevisible on either side (e.g., both sides) of the navigation array. Thismay allow a single array to function in both “left” and “right” roles bysimply rotating the array 180 degrees. Providing a single navigationarray that may serve in either “left” or “right” roles during anoperation would simplify require instrumentation and manufacturing.

FIGS. 11A-11D show another embodiment of a monolithic navigation array1110, with a frame 1102 having a plurality of navigation markers 1104that protrude from on opposite sides thereof, e.g., from both first andsecond sides of the frame. Turning to FIG. 11B, hemispherical surfacesof the navigation markers 1104 may be seen protruding from the surfaceof the frame 1104 on each side thereof. Comparing FIG. 11A and FIG. 11C,it is apparent that the array 1100 is adapted to function in both “left”and “right” roles by simply rotating the array 180 degrees, e.g.,assuming each side of the navigation markers 1104 is coated with areflective material or, alternatively, that a reflective material isembedded in each navigation marker 1104 and visible to a tracking unitfrom either side.

FIG. 11D illustrates a sectional view and a reflective element 1106 thatmay be molded into a central region of the navigation marker 1104 toenable the navigation tracker 1104 to function from both sides of thenavigation array 1100. For example, a piece of reflective material, suchas a thin sheet of metal, may be disposed in the mold and over moldedvia the injection molding process that creates the monolithic navigationarray 1100.

In certain embodiments, the molded high accuracy navigation arraysdisclosed herein may be molded over an insert formed from a differentmaterial, such as a metal, ceramic, composite, or polymer. In thismanner molding of the navigation array may be combined with an overmolding process on the insert to again create a monolithic single partthat includes the insert and over molded polymer to form a navigationarray that does not include any mechanical interface for easilydisassembling components. The insert may take a variety of forms, asdescribed in more detail below.

FIG. 12 shows another embodiment of a monolithic navigation array 1200having an over molded insert 1202, a frame 1203, and a plurality ofnavigation markers 1204. As can be appreciated, the molding processallows for tight tolerances between locations of the navigation markers1204 and a distal end of the insert 1202, for example, within +/−0.05mm. In some embodiments, the insert 1202 may be a metal, a ceramic, aplastic, or a composite, etc., integrally molded into the polymerinjection molded frame 1203. The insert 1202 may include features toprovide more secure coupling of the navigation array 1200 to a surgicalinstrument, robot arm, or other component. Alternatively, in someembodiments, the insert 1202 may itself form a surgical instrument, suchas a landmark probe that may be used in conjunction with a surgicalnavigation system to register the location of various objects in theoperating theater, such as various portions of patient anatomy, etc.

Various embodiments of distal-tip inserts that may be integrated into amonolithic navigation array via an over molding process arecontemplated.

FIG. 13 shows a cut away view of another embodiment of a monolithicnavigation array 1300 having an over molded insert 1302. The insert 1302is configured to couple with a surgical instrument or other componentand is molded into the navigation array 1300 such that a proximal end1306 thereof is over molded by a polymer frame 1304. The proximal end1306 of the insert 1302 may include any of a variety of integratingfeatures, such as portions of varying diameter with shoulder/ledgetransitions to provide greater surface area for contact between theframe 1304 and the insert 1302. This junction between the insert 1302and the frame 1304 may be designed to provide ample support to theinsert. In some embodiments, for example, the frame 1304 may be overmolded on top of the insert 1302 along a longitudinal axis thereof overa distance at least about 3 to 4 times a diameter of the insert.

FIG. 14 shows a cut away view of another embodiment of a monolithicnavigation array 1400 having an over molded insert 1402. The insert 1402is configured to operate as a landmarking probe and is molded into thenavigation array 1400 such that a proximal end 1406 thereof is overmolded by a polymer frame 1404. The proximal end portion 1406 of theinsert 1402 may include a different configuration from the insert 1302(FIG. 13), such as a knurled section of reduced diameter, again toincrease surface area contact between the insert 1402 and frame 1404 andincrease the support provided between these components. In someembodiments, for example, the frame 1404 may be over molded on top ofthe insert 1402 along a longitudinal axis thereof over a distance atleast about 3 to 4 times a diameter of the insert.

FIG. 15 shows a cut away view of another embodiment of a monolithicnavigation array 1500 having an over molded insert 1502. The insert 1502is configured to couple to a surgical instrument or other component tobe tracked and is molded into the navigation array 1500 such that aproximal end 1506 thereof is over molded by a polymer frame 1504. Theproximal end portion 1506 of the insert 1502 may include a wishbone,forked, y-shaped, or multi-branch configuration to increase surface areacontact between the insert 1502 and frame 1504 and increase the supportprovided between these components. In some embodiments, for example, theframe 1504 may be over molded on top of the insert 1502 along alongitudinal axis thereof over a distance at least about 3 to 4 times adiameter of the insert. In some embodiments, for example, the insert1502 is configured to be used with relatively shorter arrays.

FIG. 16A shows a cut away view of another embodiment of a monolithicnavigation array 1600 having an over molded insert 1602. The insert 1602is configured to operate as a landmarking probe and is molded into thenavigation array 1600 such that a proximal end 1606 thereof is overmolded by a polymer frame 1604. The proximal end portion 1606 of theinsert 1602 may include a series of grooves to increase surface areacontact between the insert 1602 and frame 1604 and increase the supportprovided between these components. Additionally, as best seen in FIG.16B, the insert 1602 includes a flat portion to help prevent relativerotation between the insert 1602 and the frame 1604. In someembodiments, for example, the frame 1604 may be over molded on top ofthe insert 1602 along a longitudinal axis thereof over a distance atleast about 3 to 4 times a diameter of the insert.

As may be appreciated, the inserts depicted in FIGS. 12-16B are notintended to be removable or disassembled from the remainder of thearray.

In some embodiments, methods of manufacturing monolithic navigationarrays include providing a sub-assembly position reflective navigationmarkers and/or provide greater rigidity to the navigation array.

FIG. 17 shows a navigation marker sub-assembly 1700 that may bepositioned within a mold and over molded with a polymer material to forma monolithic navigation array, such as monolithic navigation array 1800shown in FIG. 18. The sub-assembly 1700 may include a plurality ofsegments 1704 that connect a plurality of navigation markers 1706 (e.g.,or recesses configured to subsequently receive a transparent materialduring injection molding to form a navigation marker in the recess).Collectively, the segments 1704 and recesses could be referred to as aframe. In some embodiments, the segments 1704 may be formed from ametal. In some embodiments, the segments 1704 and recesses (to receivenavigation markers 1706) may be molded as one component (e.g., a frame)during a first molding operation to create the sub-assembly 1700. Thesub-assembly 1700 may then be positioned within a mold for thenavigation array and over molded to create a monolithic navigation array1800.

FIG. 18 shows a cut away view of the monolithic navigation array 1800molded over the navigation marker sub-assembly 1700 of FIG. 17. Thearray 1800 comprises an end 1802 (which may be an insert), an injectionmolded frame 1804, and navigation markers 1806.

FIG. 19 illustrates a method for creating a monolithic navigation array1900 similar to the array 1800 (FIG. 18) that utilizes a sub-assembly1902. The sub-assembly 1902 comprises a plurality of navigation markers1904 (referred to as reflective devices in the figure) integrated into aframe 1906. At step 1, the sub-assembly 1902 is provided (e.g., thereflective navigation markers 1904 may be molded into the frame 1906).

At step 2, a manufacturing unit 1908 (e.g., a robot or an operator)loads the sub-assembly 1902 into a mold 1910 for the final navigationarray 1900. The mold 1910 may include spaces 1912 formed in the mold toaccommodate the sub-assembly 1902 (e.g., as a network of reflectivedevices) in a correct position. In addition, specific features formed inthe mold 1910 may interact with features on the sub-assembly 1902 and/ornavigation markers 1904 and/or frame 1906 (e.g., a ring around a part)to facilitate gripping the part by manufacturing unit 1908 and/ormaintaining a position of the sub-assembly 1902 relative to the mold1910 via features formed in the mold itself.

At step 3, an injection molding operation then over molds thesub-assembly 1902 to create the finished array 1900 having navigationmarkers 1904 correctly positioned thereon to provide accurate surgicalnavigation of any component coupled to the array. A variety of materialsmay be utilized for such a procedure. For example, in some embodimentsthe navigation markers 1904 may be formed from Polyethyleneimine (PEI),which has a high heat deflection temperature. For the over mold, amaterial with an adapted molding temperature may be utilized, such asAcrylonitrile Butadiene Styrene (ABS), N,N-methylene-bis-acrylamide(MBA), Polybutylene Terephthalate (PBT), etc.

FIG. 20 shows a navigation marker sub-assembly 2000 comprising aplurality of reflective navigation markers 2002 (e.g., reflectiveelements that will serve as navigation markers in the finished array)connected by a plurality of arms 2004 in a shape to be subsequentlyover-molded to form a navigation array (such as monolithic navigationarray 2200 of FIG. 22). FIG. 21 is an elevational view of the navigationmarker sub-assembly 2000 and shows that the relative positions of eachnavigation marker 2002, as indicated by distance L2, are defined by thearms 2004. The tolerance of the navigation array frame positioning,however, does not necessarily define the resultant positional toleranceof the navigation markers.

FIG. 22 shows a cut away view of another embodiment of a monolithicnavigation array 2200 molded over the navigation marker sub-assembly2000 (of FIG. 20). More particularly, in an over-molding step, such as asingle molding operation, a material 2202 is molded around the frame2000 to form a navigation array 2200. The navigation array 2200 includesnavigation marker regions 2204 molded around the navigation markers2002. The accuracy of the positioning of the navigation marker regions2204 as indicated by L2′, is controlled by the molding step and may bemore tightly toleranced. The molding and over molding process describedherein may create integrated, monolithic, single-piece navigation arraysthat have greater tolerances than is typically encountered whenmanufacturing metal navigation array frames.

FIG. 23 shows a navigation marker sub-assembly 2300 comprising a housing2302 with voids 2304 defined therein, the voids configured to havenavigation marker regions molded therein, the relative positions of thevoids indicated by distance L3. In some instances, the navigation arraysub-assembly 2300 may be molded in a first molding operation. Examplematerials for the housing 2302 may include opaque plastics, such as PSUand PEEK.

In a second molding operation, as shown in FIG. 24, navigation markers2402 are molded into the voids 2304 with a relative tolerance, asindicated by distance L3′, that is controlled by the molding operatingand may be more tightly toleranced. Example materials for the markers2402 may be clear, such as polycarbonate. The housing 2302 materialshould have a higher molding temperature than the material for themarkers 2402. Alternatively, the method may comprise over molding themarkers 2402 with a same material as the housing 2302, such as with anacrylic material like PMMA or MBA, to have the housing form a chemicallink with markers 2402 due to limited re-melting during the secondinjection molding step.

In a final step, reflective layers or coatings 2404 are applied to anexterior surface of the navigation markers 2402 to form navigationmarkers suitable for use with a surgical tracking unit of a surgicalnavigation system.

In still other embodiments, individual components may be over moldedinto a navigation array, similar to how the inserts described above wereintegrated into a navigation array via over molding. For example, and asshown in the method diagram of FIG. 25, in some embodiments, individualnavigation markers or reflective devices 2502

FIG. 25 illustrates a method for creating a monolithic navigation array2500. At step 1, a plurality of individual navigation markers 2502(referred to as reflective devices in the figure) are provided.

At step 2, a manufacturing unit 2506 (e.g., a robot or an operator)loads the individual navigation markers 2502 into a mold 2504 for thefinal navigation array 2500. The mold 2504 may include spaces 2508formed in the mold to accommodate the navigation markers 2502. Inaddition, specific features formed in the mold may interact withfeatures on the navigation markers 2502 (e.g., interface with aperimeter ring 2510 formed around a navigation marker 2502) tofacilitate gripping the marker and maintaining its position relative tothe mold 2504.

At step 3, an injection molding operation then over molds navigationmarkers 2502 to create the finished array 2500 having navigation markers2502 correctly positioned thereon to provide accurate surgicalnavigation of any component coupled to the array. A variety of materialsmay be utilized for such a procedure. For example, in some embodimentsthe navigation markers 2502 may be formed from Polyethyleneimine (PEI),which has a high heat deflection temperature. For the over mold, amaterial with an adapted molding temperature may be utilized, such asAcrylonitrile Butadiene Styrene (ABS), N,N-methylene-bis-acrylamide(MBA), Polybutylene Terephthalate (PBT), etc.

Examples of the above-described embodiments may include the following.

In an example, a navigation array for use in a computer-assistedsurgical system comprises a monolithic array body comprising anonreflective frame region, and a plurality of spaced apart markerregions, wherein each of the marker regions has an associated reflectiveelement configured to be detected and tracked by an optical trackingsensor. The frame region and the marker regions of the monolithic arraybody may be comprised of the same material. The material may be apolysulfone polymer or a polyether ether ketone polymer. The frameregion of the monolithic array body may be comprised of a firstmaterial, and the marker regions of the monolithic array body may becomprised of a second material. The first material has a higher moldingtemperature than the second material in some examples. The firstmaterial may be an acrylonitrile butadiene styrene polymer, anN,N-methylene-bis-acrylamide polymer, a polybutylene terephthalatepolymer, a polymethyl methacrylate polymer, or anN,N-methylene-bis-acrylamide polymer. The second material may betransparent. The second material may be a polycarbonate polymer or apolyethyleneimine polymer. The marker regions of the monolithic arraybody may be each coated with the reflective element. The reflectiveelement may be embedded in each of the marker regions of the monolithicarray body. The marker regions can be detected and tracked by theoptical tracking sensor from either side of the navigation array. Themarker regions of the monolithic array body may be all similarly shaped.At least two of the marker regions of the monolithic array body havedifferent shapes. The marker regions of the monolithic array haveunequal diameters between a first side of the array and a second side ofthe array. The navigation array may further comprise an insert overmolded into the monolithic array body.

In another example, a computer assisted surgical system comprises theabove-described navigation array embodiments, an optical tracking unitassociated with at least one optical tracking sensor, and a controlunit, wherein the control unit may be adapted to utilize a predeterminedfixed geometric relationship between the marker regions and detectedpositions of the marker regions to determine a three-dimensionalposition and orientation of the navigation array. The computer assistedsurgical system may further comprise a robot arm and a surgicalinstrument mounted to the robot arm. The navigation array may be adaptedto be mounted to the robot arm or the surgical instrument.

In yet another example, a method manufacturing a navigation arraycomprises injection molding, in a single operation, the monolithic arraybody. The navigation array comprises the above-described navigationarray embodiments.

In yet another example, a method manufacturing a navigation arraycomprises over molding the monolithic array body over a navigationmarker sub-assembly. The navigation array comprises the above-describednavigation array embodiments. The sub-assembly comprises a frame.

In yet another example, a method of producing a surgical navigationarray comprises injection molding, in a single operation, a monolithicbody of a surgical navigation array, the monolithic body comprising twoor more marker regions located a distance apart from each other, andforming a navigation marker in each of the two or more marker regions bydisposing a layer on at least a rear portion of an exterior of themarker region, wherein the layer and marker region together areconfigured to be detected and tracked using a optical surgicalnavigation system. A front portion of the exterior of the marker regionin this example defines a hemispherical surface. The monolithic body inthis example comprises a non-reflective outer surface. In this example,the layer comprises a reflective surface positioned against the rearportion. The reflective surface may be reflective to at least infraredlight. The marker region may be made from a clear material that visiblyexposes the reflective surface through a front portion of the exterior.A distance between the two or more marker regions as defined by theinjection molding is accurate in this example to within 0.1 mm or less,0.075 mm or less, or preferably, 0.05 mm, or less. The monolithic bodymay comprise three marker regions in a triangular arrangement. Themonolithic body may be molded around a rigid frame. The monolithic bodymay be molded from polycarbonate.

In yet another example, a method of producing a surgical navigationarray comprises injection molding, in a single operation, a monolithicbody of a surgical navigation array on a frame comprising two or morereflective elements located apart from each other, the monolithic bodydefining a marker region around each of the two or more reflectiveelements such that the marker region and respective reflective elementtogether form a navigation marker configured to be detected and trackedusing a optical surgical navigation system, and wherein the two or morenavigation markers are located a distance apart from each other that isdefined by a position of their respective marker region in themonolithic body. The distance between the two or more marker regions asdefined by the injection molding is accurate in this example to within0.1 mm or less, 0.075 mm or less, or preferably, 0.05 mm, or less. Theframe in this example comprises three reflective elements and themonolithic body comprises a marker region around each of the threereflective elements to form three navigation markers, and the threenavigation markers are in a triangular arrangement. The frame in thisexample comprises three reflective elements, wherein the monolithic bodycomprises three marker regions, wherein each of the three reflectiveelements and a respective one of the three marker regions together froma navigation marker, and wherein the three navigation markers regionsdefine a triangular arrangement. A front portion of an exterior of eachmarker region in this example defines a hemispherical surface above arespective reflective element. The monolithic body may comprise anon-reflective outer surface. The reflective element may be reflectiveto at least infrared light. Each marker region may be made from a clearmaterial that visibly exposes the respective reflective element throughan exposed exterior surface of the marker region.

In yet another example, a method of producing a surgical navigationarray comprises injection molding, in a single operation, a monolithicbody of a surgical navigation array around two or more surgicalnavigation markers, the monolithic body securely capturing the two ormore surgical navigation markers in a define arrangement and a distanceapart from each other, wherein each surgical navigation marker isconfigured and positioned in the monolith body to be detected andtracked using a optical surgical navigation system. In this example, themonolithic body securely captures three navigation markets in atriangular arrangement. The distance between the two or more markerregions may be accurate in this example to within 0.1 mm or less, 0.075mm or less, or preferably, 0.05 mm, or less.

In yet another example, a method of producing a surgical navigationarray comprises injection molding, in a first operation, a monolithicframe of a surgical navigation array, the monolithic body defining twoor more voids, injection molding, in a single second operation, amonolithic marker element in each of the two or more voids, and forminga navigation marker from each of the two or more marker elements bydisposing a layer on at least portion of an exterior of the markerelement, wherein the layer and marker element together are configured tobe detected and tracked using a optical surgical navigation system. Inthis example, the monolithic body comprises a first material and themonolithic marker element comprises a second material that is differentfrom the first material. The first material may define a nonreflectivesurface of the monolithic frame, and the second material may be clearsuch a reflective surface of the layer is visible through the markerelement. A front portion of the exterior of the marker region may definea hemispherical surface. The monolithic body may comprise anon-reflective outer surface. The layer may comprise a reflectivesurface positioned against the rear portion. The reflective surface maybe reflective to at least infrared light. The marker region may be madefrom a clear material that visibly exposes the reflective surfacethrough a front portion of the exterior. The distance between markerelements may be accurate in this example to within 0.1 mm or less, 0.075mm or less, or preferably, 0.05 mm, or less. The monolithic body maycomprise three marker regions in a triangular arrangement.

In yet another example, a method of producing a surgical navigationarray on a frame comprises injection molding, in a single secondoperation, a two or more marker elements on the frame, and forming anavigation marker from each of the two or more marker elements bydisposing a layer on at least portion of an exterior of the markerelement, wherein the layer and marker element together are configured tobe detected and tracked using a optical surgical navigation system. Themethod may further comprise injection molding three marker elements onthe frame in a triangular arrangement and forming a navigation markerfrom each of the three marker elements. The injection molding may locateeach of the two or more market elements a respective distance from eachother that is accurate to within 0.1 mm or less. A front portion of theexterior of the marker element may defines a hemispherical surface. Theframe may comprise a non-reflective outer surface. The layer maycomprise a reflective surface positioned against the rear portion. Thereflective surface may be reflective to at least infrared light. Themarker element may be made from a clear material that visibly exposesthe reflective surface through a front portion of the exterior. Themethod may further comprise injection molding, in a single secondoperation, three marker elements on the frame and forming a navigationmarker from each of the three marker elements.

In yet another example, a surgical navigation array comprises aninjection-molded monolithic body defining a frame region and a pluralityof navigation marker regions connected by the frame region, each of thenavigation marker regions defining a clear front exterior surface and arear exterior surface, a reflective layer disposed on the rear exteriorsurface of each of the navigation marker regions, wherein each of thenavigation marker regions and a respective reflective layer formed on anavigation marker region is configured to be detected and tracked usinga surgical navigation system. The clear front exterior may form ahemispherical shape. The frame region may comprise a nonreflectiveexterior surface. The frame region may be formed from a first materialand each of the marker regions is formed from a second material that isdifferent from the first material. A rigid frame may surround theinjection-molded monolithic body. The plurality of navigation markerregions may include three navigation marker regions connected in atriangular configuration.

1. A navigation array for use in a computer-assisted surgical system,the array comprising: a monolithic array body comprising: anonreflective frame region; and a plurality of spaced apart markerregions; wherein each of the marker regions has an associated reflectiveelement configured to be detected and tracked by an optical trackingsensor.
 2. The navigation array of claim 1, wherein the frame region andthe marker regions of the monolithic array body are comprised of thesame material.
 3. The navigation array of claim 2, wherein the materialis a polysulfone polymer or a polyether ether ketone polymer.
 4. Thenavigation array of claim 1, wherein the frame region of the monolithicarray body is comprised of a first material, and the marker regions ofthe monolithic array body are comprised of a second material.
 5. Thenavigation array of claim 4, wherein the first material has a highermolding temperature than the second material.
 6. The navigation array ofclaim 4, wherein the first material is an acrylonitrile butadienestyrene polymer, an N,N-methylene-bis-acrylamide polymer, a polybutyleneterephthalate polymer, a polymethyl methacrylate polymer, or anN,N-methylene-bis-acrylamide polymer.
 7. The navigation array of claim4, wherein the second material is transparent.
 8. The navigation arrayof claim 4, wherein the second material is a polycarbonate polymer or apolyethyleneimine polymer.
 9. The navigation array of claim 1, whereinthe marker regions of the monolithic array body are each coated with thereflective element.
 10. The navigation array of claim 1, wherein thereflective element is embedded in each of the marker regions of themonolithic array body.
 11. The navigation array of claim 10, wherein themarker regions can be detected and tracked by the optical trackingsensor from either side of the navigation array.
 12. The navigationarray of claim 1, wherein the marker regions of the monolithic arraybody are all similarly shaped.
 13. The navigation array of claim 1,wherein at least two of the marker regions of the monolithic array bodyhave different shapes.
 14. The navigation array of claim 1, wherein themarker regions of the monolithic array have unequal diameters between afirst side of the array and a second side of the array.
 15. Thenavigation array of claim 1, further comprising an insert over moldedinto the monolithic array body.
 16. A computer assisted surgical system,the system comprising: a navigation array of claim 1; an opticaltracking unit associated with at least one optical tracking sensor; anda control unit, wherein the control unit is adapted to utilize apredetermined fixed geometric relationship between the marker regionsand detected positions of the marker regions to determine athree-dimensional position and orientation of the navigation array. 17.The system of claim 16, further comprising a robot arm and a surgicalinstrument mounted to the robot arm.
 18. The system of claim 17, whereinthe navigation array is adapted to be mounted to the robot arm or thesurgical instrument.
 19. A method manufacturing a navigation array ofclaim 1, comprising: injection molding, in a single operation, themonolithic array body.
 20. A method manufacturing a navigation array ofclaim 1, comprising: over molding the monolithic array body over anavigation marker sub-assembly.